A guide wire is used to facilitate insertion of a catheter into a lumen of a living body, such as the digestive tract and a blood vessel. During use, a catheter can be slipped over the guide wire.
A guide wire is also used to lead an endoscope or a catheter inserted into the lumen of an endoscope to a desired position in the lumen of a living body at the time of observation or treatment of the living body lumen. An example of such a guide wire is discussed in Japanese Patent Laid-Open No. 2007-135645.
A guide wire for this purpose includes a long wire and a coil covering the distal end of the wire. The coil may be formed from a radiopaque material such as a noble metal. The coil makes the distal end of the guide wire visible to facilitate insertion of the guide wire into a living body by radioscopy. The coil includes two parts, a first coil and a second coil, and each part is formed from a helically wound wire.
The conventional coil consisting of two parts is observed during radioscopy as one monochromatic continuous member with a certain intensity because the two parts are close to each other. This causes difficulties in locating the distal end of the guide wire being inserted into the lumen of a living body.
Moreover, the conventional coil alone does not produce a high-contrast X-ray image. This causes difficulties in locating the distal end of the guide wire and hence hinders smooth insertion of the guide wire into a living body. The fact that the guide wire is monochromatic and merely provides a low-contrast X-ray image makes it difficult to determine how far the guide wire has advanced and creates difficulties in locating the distal end of the guide wire being inserted into a living body.